A recovering crack addict was sent to prison for four-to-12 years yesterday for leaving a smoldering crack pipe on an old mattress in a Brooklyn building, which went up in flames, killing the father of a city firefighter who responded to the scene.

Jeff Lundy, 31, who had pleaded guilty to second-degree manslaughter, declined to say anything about the crime to Judge Abraham Gerges in Brooklyn Supreme Court.

The judge called the May 22, 2002, death of Richard Lang Sr., a 63-year-old retired gravedigger, at the three-story house on 17th Street, a “senseless loss” that could have been prevented had Lundy not been smoking dope.

Gerges expressed his condolences to the victim’s three sons who sat in the courtroom gallery, saying, “It is our hope that the sentence will provide a measure of closure for you.”

The sons – including firefighter Richard Lang Jr., who fought desperately that fateful night with 100 brother firefighters to put out the blaze – chose not to speak at the sentencing, saying later the pain will never go away.

“I don’t think there will ever be closure,” Lang Jr. said. “There will always be an empty void there.”

His brother Walter Lang, who had escaped the blaze with their father but said the elderly Lang had returned to the building to dial 911, said, “We got to just accept it.”

Defense lawyer John Stella noted Lundy is remorseful for having killed Lang Sr., whom he considered a friend, and has been drug-free for the past year.